This Core facility will be responsible for carrying out the preparation, storage and shipping of plant extracts, and much of the assay work run within the NPDDG. This is to include . soaking of plant materials; weighing, packaging, shipping and inventorying of plant extracts . testing of extracts for the presence of DNA damaging agents, DNA topoisomerase inhibitors and DNA polymerase beta inhibitors, in support of Programs 2. . isolation of purified DNA topoisomerase I and DNA polymerase beta for assay work . screening of samples received from NCI natural products repository . guiding the choice of extracts by the development/application of secondary discrimination assays in support of Laboratory Programs 2 . guiding the fractionation of extracts within Laboratory Program 3